Phenakite
A valid IMA mineral species - grandfathered
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About Phenakite
Formula:
Be2SiO4
Colour:
Colourless, white, yellow, pale rose
Lustre:
Vitreous
Hardness:
7½ - 8
Specific Gravity:
2.96 - 3
Crystal System:
Trigonal
Member of:
Name:
Named in 1833 by Nils Gustaf Nordenskiöld (October 12, 1792, Mäntsälä – February 2, 1866, Finnish/Russian mineralogist) from the Greek for "deceiver", φέναξ, in allusion to its being mistaken for quartz.
Although the spelling phenacite has been used in the past, the approved spelling is phenakite.
Although the spelling phenacite has been used in the past, the approved spelling is phenakite.
Type Locality:
Visit gemdat.org for Unique Identifiers
Mindat ID:
3188
Long-form identifier:
mindat:1:1:3188:8
Similar Names
| Phenaksite | A synonym of Fenaksite |
IMA Classification of Phenakite
Approved, 'Grandfathered' (first described prior to 1959)
First published:
1834
Classification of Phenakite
9.AA.05
9 : SILICATES (Germanates)
A : Nesosilicates
A : Nesosilicates without additional anions; cations in tetrahedral [4] coordination
9 : SILICATES (Germanates)
A : Nesosilicates
A : Nesosilicates without additional anions; cations in tetrahedral [4] coordination
Dana 7th ed.:
51.1.1.1
51.1.1.1
51 : NESOSILICATES Insular SiO4 Groups Only
1 : Insular SiO4 Groups Only with cations in [4] coordination
51 : NESOSILICATES Insular SiO4 Groups Only
1 : Insular SiO4 Groups Only with cations in [4] coordination
14.3.1
14 : Silicates not Containing Aluminum
3 : Silicates of Be
14 : Silicates not Containing Aluminum
3 : Silicates of Be
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Phk | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
| Phk | The Canadian Mineralogist (2019) | The Canadian Mineralogist (2019) The Canadian Mineralogist list of symbols for rock- and ore-forming minerals (December 30, 2019). download |
Pronunciation of Phenakite
Pronunciation:
| Play | Recorded by | Country |
|---|---|---|
| Jolyon Ralph | United Kingdom |
Physical Properties of Phenakite
Vitreous
Transparency:
Transparent
Colour:
Colourless, white, yellow, pale rose
Streak:
White
Hardness:
7½ - 8 on Mohs scale
Tenacity:
Brittle
Cleavage:
Distinct/Good
Distinct {1120} and imperfect {1011}.
Distinct {1120} and imperfect {1011}.
Fracture:
Conchoidal
Density:
2.96 - 3 g/cm3 (Measured) 2.96 g/cm3 (Calculated)
Optical Data of Phenakite
Type:
Uniaxial (+)
RI values:
nω = 1.65 - 1.656 nε = 1.667 - 1.67
Max. Birefringence:
δ = 0.014 - 0.017
Based on recorded range of RI values above.
Based on recorded range of RI values above.
Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
Surface Relief:
Very High (positive)
Relative to Canada balsam mounting medium (n ≈ 1.537).
Relative to Canada balsam mounting medium (n ≈ 1.537).
This shows the grain boundary and Becke line effect under plane-polarised
light, based on the contrast between this mineral's average refractive
index and the mounting medium. It does not take into account mineral
colouration.
In focus
Interference Figure:
This shows the idealized uniaxial interference figure - the conoscopic
(convergent-light, Bertrand-lens-in) view, for a grain cut with the optic axis
centred and vertical. The coloured rings are isochromatics, computed with the
same physics as the Michel-Lévy bar above; the dark cross is the isogyre.
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
Chemistry of Phenakite
Mindat Formula:
Be2SiO4
Element Weights:
Elements listed:
Crystallography of Phenakite
Crystal System:
Trigonal
Class (H-M):
3 - Rhombohedral
Space Group:
R3
Cell Parameters:
a = 12.438 Å, c = 8.231 Å
Ratio:
a:c = 1 : 0.662
Unit Cell V:
1,102.77 ų (Calculated from Unit Cell)
Z:
18
Morphology:
Flattened rhombohedra, often highly modified. Dominant forms {1120}, {1010}, {1011}, {1232}, {1123}, {2113}, {0112}. Tabular to prismatic, less commonly long prismatic to acicular to 20 cm. In columnar aggregates, as spherulites, and granular.
Twinning:
Penetration twins on {1010}, twin axis [0001].
Crystallographic forms of Phenakite
Crystal Atlas:
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Phenakite no.34 - {011} - Goldschmidt (1913-1926)
Phenakite no.65 - {110} - Goldschmidt (1913-1926)
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Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0020478 | Phenakite | Tsirelson V G, Sokolova Y V, Urusov V S (1987) An X-ray diffraction study of the electron-density distribution and electrostatic potential in phenakite Be2SiO4 Geochemistry International 24 101-110 | 1987 | natural crystal from unreported locality | 0 | 293 | |
| 0007442 | Phenakite | Hazen R M, Finger L W (1987) High-temperature crystal chemistry of phenakite (Be2SiO4) and Chrysoberyl (BeAl2O4) Physics and Chemistry of Minerals 14 426-434 | 1987 | 0 | 293 | ||
| 0007441 | Phenakite | Hazen R M, Finger L W (1987) High-temperature crystal chemistry of phenakite (Be2SiO4) and Chrysoberyl (BeAl2O4) Physics and Chemistry of Minerals 14 426-434 | 1987 | 0 | 293 | ||
| 0007440 | Phenakite | Hazen R M, Finger L W (1987) High-temperature crystal chemistry of phenakite (Be2SiO4) and Chrysoberyl (BeAl2O4) Physics and Chemistry of Minerals 14 426-434 | 1987 | 0 | 293 | ||
| 0007439 | Phenakite | Hazen R M, Finger L W (1987) High-temperature crystal chemistry of phenakite (Be2SiO4) and Chrysoberyl (BeAl2O4) Physics and Chemistry of Minerals 14 426-434 | 1987 | 0 | 293 | ||
| 0001110 | Phenakite | Downs J W, Gibbs G V (1987) An exploratory examination of the electron density and electrostatic potential of phenakite American Mineralogist 72 769-777 |  | 1987 | 0 | 293 | |
| 0007371 | Phenakite | Hazen R M, Au A Y (1986) High-pressure crystal chemistry of phenakite (Be2SiO4) and bertrandite (Be4Si2O7(OH)2) Physics and Chemistry of Minerals 13 69-78 | 1986 | 0 | 293 | ||
| 0007372 | Phenakite | Hazen R M, Au A Y (1986) High-pressure crystal chemistry of phenakite (Be2SiO4) and bertrandite (Be4Si2O7(OH)2) Physics and Chemistry of Minerals 13 69-78 | 1986 | 1.6 | 293 | ||
| 0007373 | Phenakite | Hazen R M, Au A Y (1986) High-pressure crystal chemistry of phenakite (Be2SiO4) and bertrandite (Be4Si2O7(OH)2) Physics and Chemistry of Minerals 13 69-78 | 1986 | 3.6 | 293 | ||
| 0007374 | Phenakite | Hazen R M, Au A Y (1986) High-pressure crystal chemistry of phenakite (Be2SiO4) and bertrandite (Be4Si2O7(OH)2) Physics and Chemistry of Minerals 13 69-78 | 1986 | 4.95 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Loading XRD data...
Data courtesy of RRUFF project at University of Arizona, used with permission.
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.12 Å | (100) |
| 3.66 Å | (80) |
| 2.52 Å | (70) |
| 2.36 Å | (70) |
| 2.19 Å | (60) |
| 2.08 Å | (50) |
| 6.24 Å | (40) |
| 3.60 Å | (30) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 23 : Subaerial aqueous alteration by non-redox-sensitive fluids (see also #47) | |
| Stage 4b: Highly evolved igneous rocks | >3.0 |
| 34 : Complex granite pegmatites |
Geological Setting:
In granite pegmatites and schists
Type Occurrence of Phenakite
Place of Conservation of Type Material:
Mining Institute, St. Petersburg, Russia, 617/22.
Geological Setting of Type Material:
In schist.
Synonyms of Phenakite
Other Language Names for Phenakite
Relationship of Phenakite to other Species
Member of:
Other Members of Phenakite Group:
| Eucryptite | LiAlSiO4 | Trig. 3 : R3 |
| Willemite | Zn2SiO4 | Trig. 3 : R3 |
Common Associates
Associations Based on Photo Data:
| 119 photos of Phenakite associated with Quartz | SiO2 |
| 63 photos of Phenakite associated with 'Smoky Quartz' | SiO2 |
| 58 photos of Phenakite associated with Microcline | K(AlSi3O8) |
| 54 photos of Phenakite associated with Chlorite Group | |
| 49 photos of Phenakite associated with Fluorite | CaF2 |
| 48 photos of Phenakite associated with Albite | Na(AlSi3O8) |
| 43 photos of Phenakite associated with Beryl | Be3Al2(Si6O18) |
| 32 photos of Phenakite associated with Phlogopite | KMg3(AlSi3O10)(OH)2 |
| 24 photos of Phenakite associated with Muscovite | KAl2(AlSi3O10)(OH)2 |
| 18 photos of Phenakite associated with 'Aquamarine' |
Related Minerals - Strunz-mindat Grouping
| 9.AA.05 | Eucryptite | LiAlSiO4 |
| 9.AA.05 | Willemite | Zn2SiO4 |
| 9.AA.10 | Liberite | Li2BeSiO4 |
Other Information
Thermal Behaviour:
Fusibility 7
Notes:
Insoluble in acids
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for Phenakite
mindat.org URL:
https://www.mindat.org/min-3188.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Phenakite
Reference List:
Nordenskjöld, Nils (1834) Beschreibung des Phenakits, eines neuen Minerals aus dem Ural. Annalen der Physik und Chemie, 107. 57-62 doi:10.1002/andp.18341070404
Kokscharov, Nikolai v. (1857) Ueber den Russischen Phenakit. Buchdruckerei der Kaiserlichen Akademie der Wissenschaften.
Russell, Arthur (1911) On the occurrence of Phenacite in Cornwall. Mineralogical Magazine and Journal of the Mineralogical Society, 16 (73) 55-62 doi:10.1180/minmag.1911.016.073.08
Schaller, W. T. (1911) Krystallographische Notizen über Albit, Phenakit und Neptunit. Zeitschrift für Krystallographie, 48 (1-6). 552-560 doi:10.1524/zkri.1911.48.1.552
Schaller, W. T. (1911) Mineralogical notes, series 1. Bulletin 490. US Geological Survey 109 pp. doi:10.3133/b490
Russell, Arthur (1920) On the occurrence of Phenacite and Scheelite at Wheal Cock, St. Just, Cornwall. Mineralogical Magazine and Journal of the Mineralogical Society, 19 (88) 19-22 doi:10.1180/minmag.1920.019.88.06
Lee, Donald E.; Erd, Richard C. (1963) Phenakite from the Mount Wheeler area, Snake Range, White Pine County, Nevada. American Mineralogist, 48 (1-2). 189-193
Burt, Donald M. (1978) Multisystems analysis of beryllium mineral stabilities: the system BeO-Al2O3-SiO2-H2O. American Mineralogist, 63 (7-8) 664-676
Hazen, Robert M., Au, Andrew Y. (1986) High-pressure crystal chemistry of phenakite (Be2SiO4) and bertrandite (Be4Si2O7(OH)2) Physics and Chemistry of Minerals, 13 (2) 69-78 doi:10.1007/bf00311896
Hemingway, Bruce S., Barton, Mark D., Robie, R. A., Haselton, H. T. (1986) Heat capacities and thermodynamic functions for beryl, Be3Al2Si6O18, phenakite, Be2SiO4, euclase, BeAlSiO4(OH), bertrandite, Be4Si2O7(OH)2, and chrysoberyl, BeAl2O4. American Mineralogist, 71 (3-4) 557-568
Downs, James W., Gibbs, G. V. (1987) An exploratory examination of the electron density and electrostatic potential of phenakite. American Mineralogist, 72 (7-8) 769-777
Hofmeister, A. M., Hoering, T. C., Virgo, D. (1987) Vibrational spectroscopy of beryllium aluminosilicates: Heat capacity calculations from band assignments. Physics and Chemistry of Minerals, 14 (3) 205-224 doi:10.1007/bf00307985
Pilati, T., Demartin, F., Gramaccioli, C. M. (1998) Lattice-dynamical evaluation of atomic displacement parameters and thermodynamic functions for phenakite Be2SiO4. Physics and Chemistry of Minerals, 26 (2). 149-155 doi:10.1007/s002690050171
Localities for Phenakite
Showing 433 localities.
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and further information on this occurrence.
? - Indicates mineral may be doubtful at this locality.
- Good crystals or important locality for species.
- World class for species or very significant.
(TL) - Type Locality for a valid mineral species.
(FRL) - First Recorded Locality for everything else (eg varieties).
All localities listed without proper references should be considered as questionable.
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Phenakite Mine, Khetchel village, Molo quarter, Momeik Township, Kyaukme District, Shan State, Myanmar